Protein quantification plays a pivotal role in biopharmaceutical development, particularly during the screening of cell culture supernatants. Traditional methods, such as high-performance liquid chromatography (HPLC), provide reliable measurements but suffer from low throughput and extensive time requirements. To address these limitations, a novel approach utilizing Bio-Layer Interferometry (BLI) has emerged, enabling rapid and precise quantification of Fc-fusion proteins.
Transitioning to Bio-Layer Interferometry
Biogen IDEC has pioneered a BLI-based assay specifically designed for measuring Fc-fusion proteins in cell culture supernatants. This method not only matches the accuracy of HPLC but also significantly enhances throughput. The BLI assay allows for the simultaneous testing of up to 96 samples in under five minutes, drastically reducing the time needed for results by over 90%.
The need for a more efficient technique arose from the challenges faced by the cell line development group at Biogen IDEC, which relied on HPLC for quantifying proteins during the selection of mammalian clones. The cumbersome nature of HPLC, characterized by complex sample preparation and long analysis times, prompted the search for a more efficient alternative.
Advantages of the Octet System
The Octet®QK384 instrument was selected as a replacement for HPLC due to its suitability for screening proteins directly from crude cell culture supernatants. This system eliminates the need for extensive sample pre-processing, allowing researchers to analyze a batch of 96 samples in less than half an hour, a task that would otherwise take more than 19 hours with HPLC.
By integrating the Octet system with a PerkinElmer Sciclone robot, Biogen IDEC achieved a higher-throughput, automated screening process, which minimized the need for analyst intervention. The results from this new method for quantifying Fc-fusion proteins are documented in this article.
Assay Development and Validation
The assays conducted utilized both Protein A and Protein G biosensors, chosen for their specificity in detecting Fc-fusion proteins. During assay development, researchers generated standard curves by diluting purified Fc-fusion proteins across a range of concentrations, from 0 to 100 μg/mL. The consistency of results was emphasized, with the average coefficient of variation (CV) remaining below 9% across various concentrations.
To ensure the robustness of the assay, additional tests evaluated well-to-well variability, confirming uniform performance across different sample wells. The system’s ability to handle various concentrations of cell culture media further validated its applicability in upstream processes.
Investigating Matrix Interference
An important consideration in assay development is the potential interference from matrix components. Biogen IDEC conducted tests to determine the assay’s performance when subjected to different dilutions of cell culture media. The results indicated that the assay could tolerate up to 100% cell culture media without compromising accuracy, achieving overall recoveries and CVs well within acceptable limits.
In further tests, Fc-fusion proteins were spiked into cell culture media and host cell protein matrices at various concentrations. The assay demonstrated high recovery rates, validating its accuracy under different conditions.
Ensuring Dilution Linearity
Dilution linearity is crucial for assays dealing with varying protein concentrations. The Octet assay was evaluated by diluting samples at different levels, confirming excellent linearity and consistent recoveries. The CV for the back-calculated values of the low-concentration samples was maintained below 7%, while higher concentration samples exhibited CVs below 5%.
Comparing Methods: Octet vs. HPLC
To assess the reliability of the Octet assay as a potential replacement for HPLC, a comparison study was conducted. Samples were prepared identically for both methods, ensuring consistency throughout the analysis. The results showed that titer values obtained from the Octet system were highly comparable to those from HPLC, with differences typically within 10-12%.
The Octet method facilitated a significantly faster analysis time of fewer than 10 minutes for 15 samples, compared to the 180 minutes required for HPLC.
Precision and Consistency of the Octet Assay
The precision of the Octet assay was further validated by conducting tests on different days with various analysts. The findings showcased an impressive overall CV of less than 5% across numerous runs, reinforcing the reliability of the method for consistent protein quantification.
Conclusion
The development of the BLI-based assay for quantifying Fc-fusion proteins signifies a major advancement in biopharmaceutical processes, allowing for rapid and accurate screening of cell culture supernatants. This innovative approach not only streamlines the workflow but also enhances the reliability of results, making it a vital tool in Biogen IDEC’s cell line development efforts. As ongoing investigations explore the expanded applications of this technology, the future looks promising for efficient protein quantification in therapeutic development.
- Key Takeaways:
- BLI offers rapid results compared to HPLC, reducing time-to-results by over 90%.
- The Octet system enables high-throughput analysis without extensive sample preparation.
- The assay maintains high accuracy and precision, even in complex matrices.
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